The structure of known crane systems is frequently divided into an undercarriage and a superstructure. Both components are coupled to one another via a slewing gear for rotational movements of the superstructure relative to the undercarriage. The slewing gear includes one or more drive motors for producing a rotational movement which is hydraulically braked as required in normal operation via the installed drive.
In emergency situations, the hydraulic drive is deactivated, for example by means of a complete rotation, and the rotational movement is stopped by one or more stopping brakes installed at the slewing gear. In emergency situations, the stopping brakes enable the introduction of the required braking torque to the slewing gear to achieve an interruption of the rotational movement as quickly as possible.
In the currently used braking systems for slewing gears, it is, however, the case that on the actuation of an emergency signal, the corresponding braking torque begins abruptly and the rotational movement of the slewing gear is stopped sharply. Since the superstructure as a rule has a solid and sluggish crane structure, substantial damage to the crane mechanism can occur on an abrupt stopping of the rotational movement.
A possible solution approach is shown in DE 10 2008 056 022 B3 which proposes a crane slewing gear having a plurality of independently actuable stopping brakes. In the case of an emergency stop event having occurred, the brakes are actuated sequentially in time, which allows a moderated braking of the slewing gear. It is, however, disadvantageous in this solution that a slewing gear having a plurality of stopping brakes is a required for its implementation. The solution approach shown is, in contrast, not usable for crane slewing gears having only one stopping brake.
It is the object of the present disclosure to provide a hydraulic braking apparatus for a crane drive which overcomes the problems explained above.
This object is achieved by a hydraulic braking apparatus for a crane drive for carrying out crane work having a braking apparatus. The braking apparatus accordingly includes at least one hydraulic stopping brake for braking the drive movement of the crane drive in an emergency situation. The crane drive may in particular be a slewing gear. In this case, the rotational movement of the slewing gear may be braked by the braking apparatus in accordance with the present disclosure.
The embodiment is, however, not restricted to a slewing gear. The use of the braking apparatus in accordance with the present disclosure is generally conceivable in any type of crane drives for carrying out the crane work. This includes inter alia a hoisting gear or also a retracting mechanism.
In accordance with the present disclosure, at least one stopping brake is controlled via at least one provided pressure regulation valve to ensure a time-delayed braking torque build-up.
The principle in accordance with the present disclosure applies equally to stopping brakes which achieve a braking effect due to a pressure build-up or pressure drop. The advantage of the present disclosure which is material to the present disclosure comprises the fact that the pressure variation takes place in a regulated manner over time in the supply pressure of the stopping brake due to the pressure regulation valve used and therefore takes place with any desired time delay. The engaging braking torque of the stopping brake consequently does not start immediately, but is rather built up over a definable time period. As a rule, however, use is made of stopping brakes which achieve a braking effect due to a pressure drop since a pressure loss can particularly be assumed in emergency situations.
In contrast to this, the control of such stopping brakes takes place as a rule in crane drives known from the prior art directly via a ski selector valve which either abruptly stops or immediately switches through the supply pressure to the stopping brake. The maximum possible braking torque is accordingly applied almost without delay.
At least one pressure regulation valve is controlled via at least one control pressure line to control the pass-through volume of the supply pressure line to the stopping brake. The control pressure line is preferably coupled via at least one ski selector valve to the supply pressure line of the stopping brake. In this case, the pressure valve is designed as a directly controlled pressure regulation valve. The use of an electrically controllable 4/2 ski selector valve is expedient. In the normal case, the control pressure line of the pressure regulation valve is connected to the supply pressure line; the control pressure then corresponds to the pressure level of the supply pressure line. The actuation of the ski selector valve, for example to trigger an emergency stop, effects a switching through of the control pressure line to a return tank.
Alternatively, the pressure regulation valve can be designed as a precontrolled pressure valve. In this case, the control pressure line of the pressure regulation valve is coupled to the backflow outlet of the pressure regulation valve.
It can be expedient for safety reasons that at least one pressure store is arranged in the supply pressure line of the stopping brake. For example, a complete pressure failure in the supply pressure line can occur due to a hydraulic defect. The arranged energy store can compensate the abrupt pressure drop at least at times in order nevertheless to be able to ensure a braking torque building up with a time delay. The pressure store is preferably designed as a bubble storage. Alternative embodiments are nevertheless conceivable.
To delay the pressure drop within the control pressure line of the pressure regulation valve in time, it can be expedient that at least one energy store is connected or connectable to the control pressure line. The pressure drop in the control pressure line is triggered via a corresponding switch position of the ski selector valve. The immediate pressure drop can be compensated over a specific time period via the stored pressure volume of the energy store to delay the pressure drop of the control pressure in time.
At least one used stopping brake of the crane drive can be designed as a multi-disk brake, as a band brake or as a disk brake. The basic principle material to the present disclosure of the present disclosure is in this respect independent of the present embodiment of the stopping brake used.
The stopping brake expediently engages at the output of at least one drive motor of the crane drive.
The present disclosure furthermore relates to a crane having at least one crane drive for carrying out the crane work, with the crane including in accordance with the present disclosure at least one hydraulic braking apparatus in accordance with one of the above-explained embodiments. The crane evidently accordingly has the same advantages and properties as the claimed hydraulic braking apparatus in accordance with the present disclosure so that a repeated explanation is dispensed with at this point.
The crane has a slewing gear and/or a hoisting gear and/or a retraction mechanism which is/are equipped with corresponding drives and likewise have more than one hydraulic braking apparatus.
Further advantages and details of the present disclosure will be explained in more detail in the following with reference to the drawings.